Does someone who is using VMware workstation9 have the mouse back and forward buttons working problem?
I have imwheel in my box, it works on X environment but not working on VMware workstation.
Could someone please share your solution if you have got this issue sorted?

Thanks_________________No Rolex on my wrist Or platinum on my chest 'Cause I don't need that shit to impress

The latest version of vmware-workstation finally gives us a working back & forward mouse button setup.
Need to add these lines to your vmx file

mouse.vusb.enable = "TRUE"
usb.generic.allowHID = TRUE

next emerge xbindkeys

place this in your home file

# For the benefit of emacs users: -*- shell-script -*-
###########################
# xbindkeys configuration #
###########################
#
# Version: 1.8.0
#
# If you edit this file, do not forget to uncomment any lines
# that you change.
# The pound(#) symbol may be used anywhere for comments.
#
# To specify a key, you can use 'xbindkeys --key' or
# 'xbindkeys --multikey' and put one of the two lines in this file.
#
# The format of a command line is:
# "command to start"
# associated key
#
#
# A list of keys is in /usr/include/X11/keysym.h and in
# /usr/include/X11/keysymdef.h
# The XK_ is not needed.
#
# List of modifier:
# Release, Control, Shift, Mod1 (Alt), Mod2 (NumLock),
# Mod3 (CapsLock), Mod4, Mod5 (Scroll).
#

# The release modifier is not a standard X modifier, but you can
# use it if you want to catch release events instead of press events

# By defaults, xbindkeys does not pay attention with the modifiers
# NumLock, CapsLock and ScrollLock.
# Uncomment the lines above if you want to pay attention to them.

you will need to run xev in a terminal to see what button numbers are assigned to your side buttons, the above file is from my host computer b:8 and b:9 respectively but on my vm those buttons show up as button 16 and button 17, so long as xev shows a button number when you press your side buttons, this will work.

next go to your system settings and set xbindkeys to autostart, how that works depends on your desktop session (gnome or kde)